The invention relates to memory devices that allow non-volatile storage of data in a relatively compact module using solid state electronic devices that may be used in place of disk drive devices, for example, in computing systems, data processing and network. The new memory module may use NAND flash memory devices attached to printed circuit boards (PCB) using surface mount technology that may be connected in parallel to a NAND flash controller device attached adjacent to the input/output of the memory module. The memory module may be assembled as multiple PCB's stacked adjacent, spaced apart and interconnected with PCB spacers intermediate adjacent PCB.
NAND flash memory devices have found acceptance for use in data storage applications requiring relatively small capacity, standard from factor PCB or substrate elements that may allow use of one to four memory devices for storage capacity of up to 64 gigabytes. The NAND flash memory devices may be attached to a PCB and have data input/output (I/O) communicated through a NAND flash controller for distribution through parallel I/O data lines to selected memory devices. In use where larger data storage using NAND flash memory devices may be desired, multiple PCB memory units may be used with cables, mid-planes, connectors and adapters to interconnect with the data I/O source. This type of structural architecture may lead to bulky, complex, reduced speed/performance of a flash memory system. While a single PCB flash memory unit may have up to 64 gigabytes of memory capacity as a non-volatile standard form factor devices, there is a need for larger capacity, non-volatile memory storage module.
There may be high I/O, high density, low cost electronic modules that use high density memory devices such as RAMBUS devices with a high speed serial bus to obtain high data throughput using multiple RAMBUS devices. However, this type of architecture requires use of impedance controlled buses with terminating circuitry to match the bus transmission characteristics. While such impedance control can be implemented on a RAMBUS PCB or on a motherboard/host PCB, this is an added complexity, performance element for use of high speed serial buses that is not present with the use of parallel connected memory storage devices.
The memory devices in a RAMBUS architecture are serially connected to a bus that may allow close location of multiple devices to a host chip or device. However, as mentioned above the use of a high speed data bus throughout the RAMBUS module creates other design issues that must be taken into account. The use of a parallel data bus architecture, such as, NAND flash memory device used with a NAND control, may more easily allow assembly of a compact memory module that can be located close to a host chip of a processor and may provide throughput equivalent to RAMBUS architecture and disk drive memory devices. RAMBUS memory devices are generally volatile memory storage devices.